Knee joint prosthesis

Claim 2

A prosthetic knee joint device comprising: a femoral component including a shell bearing member having two first elongate portions and a first bridge portion, said first elongate portions each being of generally U-shaped form in the longitudinal direction and generally dished form in the lateral direction, and the curvatures of such forms being of the same sense to provide a smooth major surface of overall convex curvature for each of said first elongate portions, said first elongate portions being disposed in spaced side-by-side longitudinal relation, said first bridge portion integrating said first elongate portions in continuous manner partway along the U-bases and along one pair of corresponding U-arms thereof, and said major convex surfaces follow a generally spiral curvature in their longitudinal directions with increasing radius of curvature towards their non-bridged ends, and a tibial component including a platform bearing member having two second elongate portions and a second bridge portion, said second elongate portions each having a major surface of generally dished form in both the longitudinal and lateral directions to provide smooth overall concave curvature, said second elongate portions being disposed in spaced side-byside longitudinal relation; said second bridge portion integrating said second elongate portions in continuous manner partway therealong from one pair of corresponding ends, and said major concave surfaces follow a more uniform curvature in their longitudinal directions than do said major convex surfaces, with said major concave surfaces being more congruous with the bridged ends of said major convex surfaces, said femoral and tibial components being disposed in mutual bearing relationship with their respective bridge portions generally superposed and their respective non-bridged elongate portion convex and concave surfaces engaged for mutual sliding and rotation along the longitudinal directions thereof; and wherein the major surfaces of said components opposite to said convex and concave surfaces are adapted by the provision of shallow configurations thereon for respective fixation to the femur and tibia by a gap-filling agent.

Claim 3

A device according to claim 1 wherein said first bridge portions defines a first trough, relative to said convex curvature, between said first elongate portions integrated thereby; and said second bridge portion defines a ridge relative to said concave curvature, between said second elongate portions integrated thereby.

Claim 4

A device according to claim 1 wherein said convex surfaces are generally divergent in their longitudinal directions from their bridged ends, and said concave areas are similarly divergent.

Claim 5

A device according to claim 1 wherein said femoral component is adapted for fixation to the femur with a gap-filling agent by the provision of a plurAlity of relatively short members projecting from the major surface thereof opposite to said convex surfaces.

Claim 6

A device according to claim 1 wherein said tibial component is adapted for fixation to the tibia with a gap-filling agent by the provision of a grooved formation on the major surface thereof opposite to said concave surfaces.

Claim 7

A device according to claim 5 wherein each groove of said grooved formation has a dovetail cross-sectional form.

Claim 8

A device according to claim 5 wherein said grooved formations define generally central regions of the respective surfaces of said second elongate portions which central regions extend further than the remainder of such surfaces to define plateaus.

Claim 9

A device according to claim 1 wherein said femoral and tibial components are respectively made of metal and plastics material.

Claim 10

A prosthetic knee joint device, comprising a femoral component and a tibial component; the femoral component being a shell having two laterally spaced convex bearing surfaces respectively closely conforming to the surface shapes and spatial orientation of the femoral condyles of the natural knee joint, and having a trough portion bridging between the two bearing surfaces adjacent their respective convergent ends for receiving and guiding the patella and associated tendon should these be retained; the tibial component being a platform having two laterally spaced concave bearing surfaces closely conforming to shapes developed from menisci of the natural knee joint in a plurality of different phases of rotation thereof, with one pair of corresponding end portions of said concave bearing surfaces respectfully closely conforming to the surface shapes of the anterior aspect of said menisci when said natural knee joint is in a rotational phase of relatively full extension, the other pair of corresponding ends of said concave bearing surfaces similarly conforming to the surface shapes of the posterior aspect of said menisci when said natural knee joint is in a phase of relatively full flexion, and intermediate portions of said concave bearing surfaces between the respective ends smoothly bridging therebetween, said concave bearing surfaces being dished both longitudinally and laterally, the corresponding anterior end portions of said platform being held in spaced, side-by-side relation by a bridge portion which forms a ridge between the concave dished surfaces and extends into the trough of said femoral component when these two components are engaged in a bearing relation representing maximum extension; the convex bearing areas being longer than the concave bearing areas and being generally U-shaped longitudinally and low relief protuberance and recess means formed on the reverses of the two components from the bearing surfaces, for keying, spacing and permitting resin fixation of the components without need for removal of so large amounts of bone from the natural knee joint of the patient as is generally the case with hinged forms of knee joint prostheses and without lengthy excursions of foreign material along the medullary canals.

Claim 11

A prosthetic knee joint device, comprising a femoral component and a tibial component; the femoral component being a shell having two laterally spaced convex bearing surfaces respectively closely conforming to the surface shapes and spatial orientation of the femoral condyles of the natural knee joint, and having a trough portion bridging between the two bearing surfaces adjacent their respective convergent ends for receiving and guiding the patella and associated tendon should these be retained; the tibial component being a platform having two laterally spaced concave bearing surfaces closely conforming to shapes developed from menisci of the natural knee joint in a plurality of different phases of rotation thereof, with one pair of corresponding end portions of said concave bearing surfaces respectfully closely conforming to the surface shapes of the anterior aspect of said menisci when said natural knee joint is in a rotational phase of relatively full extension, the other pair of corresponding ends of said concave bearing surfaces similarly conforming to the surface shapes of the posterior aspect of said menisci when said natural knee joint is in a phase of relatively full flexion, and intermediate portions of said concave bearing surfaces between the respective ends smoothly bridging therebetween, said concave bearing surfaces being dished both longitudinally and laterally, the corresponding anterior end portions of said platform being held in spaced, side-by-side relation by a bridge portion which forms a ridge between the concave dished surfaces and extends into the trough of said femoral component when these two components are engaged in a bearing relation representing maximum extension; the convex bearing areas being longer than the concave bearing areas and being generally U-shaped longitudinally and low relief protuberance and recess means formed on the reverses of the two components from the bearing surfaces, for keying, spacing and permitting resin fixation of the components without need for removal of so large amounts of bone from the natural knee joint of the patient as is generally the case with hinged forms of knee joint prostheses and without lengthy excursions of foreign material along the medullary canals.